The invention relates to an implant, in particular a dental implant, with an anchoring region (12) for anchoring in a bone, which preferably has a thread (14) for screwing into the bone, and with a fastening region (22) for fastening a supra-construction.
Dental Implants are in use in dentistry for decades.
Generally, dental implants are provided with an anchoring region having a threaded section, which is designed for screw-fastening in the bone. Further, a dental implant generally has a fastening region to which a supra-construction can be secured.
In one-piece implants, an extension (also referred to as an abutment) is provided, which protrudes from the anchoring region and to which supra-constructions can be attached. In the case of two-piece implants, a specifically designed recess is provided, to which an abutment can be fastened by screws or through form-fit.
Further, there are various constructions in which an additional thread is provided at the upper end of the anchoring region, which is finer than the thread in the lower region (Specifically, compare EP 2 656 813 A1, DE 10 2012 105 873 A1, WO 2014/091345 A2, WO 2003/015654 A1), or, which is coarser than the thread in the lower part of the anchoring region (Ep 1 764 060 A1).
According to WO 2003/015654 A1, at the upper end of the anchoring region, which is provided with a self-tapping thread, a fine-thread section is provided, which is preferably also slightly conical.
Through the fine thread section, the problem of bone resorption can be mitigated.
Several factors play a role in the long-term stability of implants. A sufficient osseointegration should be improved by a specific microstructure of the outer surface of the implant, wherein a semi-rough surface, produced by, for example, sandblasting, is advantageous. Even if the implant is initially well osseointegrated, there is often a noticeable pre-implant bone loss in course of time, due to which the long-term stability of the implant is impaired.
To this end, there have been on convincing approaches.
Addressing the current background, the invention is based on the objective of disclosing an implant which results in improved osseointegration, and which leads to minimum pre-implant bone loss.
The problem is solved by an implant, specifically a dental implant with an anchoring region for anchoring in a bone, which preferably has a thread for screwing into the bone, and with a fastening region for fastening a supra-construction, wherein an abutment region adjoining the anchoring region is provided, which has a guide structure with multiple outwardly projecting ridges on its outer surface.
The objective of the invention would be achieved in this manner.
It has been shown that the guide structure in the abutment region, with multiple outwardly projecting ridges, improves the osseointegration on one hand, reduces the pre-implant bone loss on the other end. The guide structure allows the bone tissue to grow or accumulates along the abutment region. To ensure a continuous bone accumulation, a broad area of bone is required. For this, the guide structure provides the necessary prerequisites.
According to another embodiment of the invention, a respective groove is formed between adjoining ridges.
According to an embodiment, the ridges extend at an angle to the longitudinal axis of the implant, which lies between 0° and 80°, preferably between 10° and 70°, more preferably between 20° and 60°, particularly preferably 35° and 55°.
This implies that the ridges can extend parallel to the longitudinal axis of the implant, or at a large or small angle to the longitudinal axis.
In contrast to the threaded structures known in the prior-art, the currently disclosed guide structure is not a thread. Threads cited in the prior-art are single-start threads with self-locking. Even if the guide structure in accordance with the invention would be interpreted as a multi-start thread, it differentiates itself from the threads known in the prior-art due to its multi-start feature. Additionally, in contrast to the threads in the prior-art, the self-locking feature is absent.
Self-locking does not require a considerably large pitch angle. The ridges of the guide structure can extend deviating from a path parallel to the longitudinal axis of the implant (i.e., at an angle of 0° to the longitudinal axis of the implant) angle at a maximum of 80° to the longitudinal axis of the implant, but significantly lower, with a maximum of 70° or 60°, making self-locking not possible.
In a further embodiment of the current invention, at least six, preferably at least ten, more preferably about 12 to 40 ridges are arranged along the outer surface of the abutment region, at regular or even intervals with respect to one another.
In contrast to a multi-start thread structure, the guide structure of the abutment region is provided with at least six or more ridges.
According to a further embodiment of the invention, the ridges extend helically or spirally along the outer surface of the abutment region.
In this manner, the ridges extend without interruption along the outer surface of the abutment region.
Further, the ridges can be inclined in a similar direction as a thread within the anchoring region, opposite to the longitudinal axis of the implant. Basically, an inclination in a reverse direction is also possible.
According to a further embodiment of the invention, in a planar development of the abutment region, the ridges extend convexly from the anchoring region, towards the end of the abutment region (coronal end) located distal to the anchoring region.
In such an embodiment, too, an augmentation can be secured through a screw movement, over the abutment region.
In accordance with another embodiment of the invention, the abutment region has a convex or a conical outer contour.
Such an embodiment has an advantage that only a linear or an interrupted linear contact region to the bone is provided, due to which the accumulation of the bone can be facilitated.
In a modification to the above-mentioned uninterrupted structure of the ridges, these ridges can also be interrupted.
According to a further modification of the invention, the ridges are formed from a series of projections arranged along a line.
The osseointegration hereby can be further improved, since an overall improved implantation of the bone structure can be achieved and locally elevated surface pressures are diminished.
According to a further modification of the invention, a first sequence of ridges extends parallel to one another along the abutment region, around the entire outer circumference, which is adjoined by a second sequence of ridges also extending parallel to one another along the entire outer circumference of the abutment region, where the second sequence of ridges is aligned or staggered to the first sequence of ridges.
According to a further embodiment of the invention, individual ridges are arranged at an offset relative to one another along the outer circumference, though arranged parallel to one another.
In a further modification of the invention, individual interrupted ridges are arranged between adjacent uninterrupted ridges.
In a further modification of the invention the individual ridges are arranged at an angle to one another in a regular pattern along the outer surface.
All of the embodiments mentioned herein are adapted to support improved osseointegration and reduce the peri-implant bone loss.
According to a further embodiment of the invention, the abutment region is provided to protrude from a borehole in the bones.
In this manner, the bone can attach itself well to the implant, in the abutment region adjacently adjoining the anchoring region, outside the screwed region, the screwed region being formed by the thread of the anchoring region.
According to a further embodiment of the invention, the abutment region is provided for anchoring an augmentation.
The augmentation can be arranged around the abutment region, or according to its structure, can be fixed to a certain manner.
The attachment of the augmentation to the abutment region is, therefore, advantageous when the bone strength is no longer sufficient to accommodate the minimum length of the implant, which is approximately 8 to 12 mm. Further, the abutment region is optimally suited and adapted to ensure safe osseointegration of the augmentation.
According to a further embodiment of the invention, the grooves exhibit a depth lower than the starts of a thread at the anchoring region.
It has been shown that a relatively small depth of the grooves is particularly advantageous for favorable osseointegration.
According to a further embodiment of the invention, the outer circumference at the anchoring region is greater than or equal to the outer circumference at the abutment region.
In this manner, when the implant is screwed in by means of the thread provided at its anchoring region, it is avoided that the abutment region also cuts into the bone. In this way, an optimal osseointegration at the abutment region is accomplished.
The implant in accordance with the invention can principally be designed either as a one-piece or a multi-piece implant. When it is designed as a double-piece implant, the fastening region preferably has a recess with fastening element for fastening an abutment.
Herein, an internal thread or at least one form-fitting element can be provided in the recess, for fastening an abutment.
In this case, the recess preferably extends outwardly from one end of the abutment region into the abutment region.
On the other hand, if the implant is designed as a one-piece implant, the fastening region protrudes outwards from the abutment region, and is designed as one-piece with the abutment region and the anchoring region.
Stated otherwise, the fastening region is designed as an abutment, which protrudes outwardly from the abutment region.
The implant preferably consists of ceramic, in particular of a zirconium oxide ceramic.
It has been found that surfaces with a particularly good osseointegration can hereby be provided. Also, such a material selection is particularly suitable for reconstructions in the anterior tooth area, as the color of the ceramic, such as zirconium oxide ceramic, strongly matches the natural tooth color.
In an alternative embodiment, the implant consists of a metallic material/alloy, in particular a titanium alloy. The implant may also consist of various alloys or gradient materials. Further, it is also possible to manufacture in 3D-printing from metal or ceramic.
This yields very good mechanical stability and ease of manufacturing.
According to a further embodiment of the invention, the implant is roughened on its outer surface, in particular mechanically by means of a radiation treatment, chemically by means of an etching treatment, or thermally by means of a laser treatment or through plasma treatment.
Additionally, the implant can be a chemically activated on its outer surface, in particular by means of an etching treatment or by application of a substance having affinity to bones.
By means of such surface treatment, including the treatment of the outer surface of the anchoring region and the abutment region, a substantially improved osseointegration can be achieved.
According to a further embodiment of the invention, the anchoring region has a first length in axial direction and the abutment region has a second length in the axial direction, wherein the first length is at least as large as the second length.
Herein, the first length can also be larger than the second length.
Here, preferably the second length can be approximately between 3 to 10 mm, wherein the cumulative length of the anchoring region and the abutment region can be at most 15 mm.
Depending on the application, this is the optimal length for the abutment region.
Finally, the ridges can either have a flattened or rounded at their outer surface.
This also supports accumulation of the bone.
Further, the invention provides a method for implanting an implant, comprising the following steps:                Producing a recess in the bone which is adapted for receiving the anchoring region, in particular by drilling, ultrasonic cutting or laser cutting;        screwing the implant into the bore in such a way that the abutment region either terminates at the bone level or protrudes beyond the bone only by a small amount, preferably by about 0.5 mm to 2 mm.        
This variant is particularly preferred when sufficient bone-substance is available and no reinforcement through an augmentation is required.
On the other hand, if a reinforcement through an augmentation is required, the implantation can occur in the following manner:                Forming a recess in the bone by drilling, ultrasonic cutting or laser cutting, the recess being adapted to receive the anchoring region;        Anchoring the implant into the bone in a manner that abutment region protrudes beyond the bone by a small amount, preferably by about 1 mm to 10 mm, more preferably by 3 mm. to 10 mm;        Securing an augmentation in the abutment region.        
It is obvious that the features of the invention mentioned above can not only be used in the particular combination indicated but also in other combinations and variations without departing from the scope of the invention.